1. Field of the Invention
The present invention refers to a cord-locking device for releasably gripping a cord, comprising a grip member arranged to receive the cord and be held releasably by a holding member.
Such a cord-locking device may be used for many purposes, preferably it may be used as a safety coupling, wherein the grip member of the cord-locking device and the holding member may be pulled apart when the coupling device is subjected to great pulling loads.
2. Description of the Prior Art
An example of an application field is milking machines provided with a device for automatic removal of a milking member from the teats of the animal which is milked. For such removing devices, an air cylinder having a movable piston which via a cord is connected to the milking member is usually utilized. Sometimes, it happens that the cow tries to kick off the milking member, wherein the legs may get entangled in the cord. In order to solve this problem, it is known to utilize a safety device which in case of large loads releases the cord, wherein injuries on the cows and damage to the milking members may be avoided.
Such a safety device is known from SE,B,453 217, which comprises a coupling device which may be pulled apart as a consequence of large loads. The coupling device comprises male and female members which may be screwed together. Cords are attached to a respective member through holds and maintained by knots provided on the cords. The disadvantage of this device is that the loosely hanging member parts may cause injuries on the cows and the milking members when the coupling device is pulled apart. Moreover, said knots may get stuck on inappropriate locations and cause injuries.
A cord-locking device is previously known from WO95/05733, which comprises a grip member arranged to receive the cord and to be loosely held by a holding member. The grip member comprises a through-going hole in which the cord is fastened by a knot. When the grip member is pulled apart from the holding member, the grip member will also in this case hang on the lose cord and cause injuries on cows and damage to the milking equipment.
The purpose of the present invention is to provide a cord-locking device of the kind initially defined, by which the above-mentioned disadvantages of previously known cord-locking devices may be remedied to a large extent, and thereby eliminate the risks for injuries on cows and damage on the equipment of the milking machine when the cord is subjected to unusually large pulling loads. Furthermore, it is aimed a cord-locking device which enables releasable locking of an even cord, i.e. a cord which is not provided with knots or the like.
This object is obtained according to the invention by the features that the grip member, held by the holding member, is arranged to lock fixedly the received cord by clamping as a consequence of a pulling load applied to the cord, and that the grip member, when released from said holding member, is arranged to enable the release of the received cord from the grip member.
By this design, it is obtained that the cord in an essentially even state may be fastened in the grip member without knots and that, when the grip member is pulled off from the holding member, the received cord is released from the grip member which falls down to the ground and thereby does not constitute any risks for the cow and the milking device.
According to a preferred embodiment of the invention, the grip member comprises a passage for said receiving of the cord. Furthermore, the grip member may comprise a locking portion, which is arranged to lock fixedly the cord in the passage as a consequence of a pulling load applied to the cord. Preferably, the locking portion is resilient and displaceable in the grip member. By this design, it is possible to lock the cord in the passage of the grip member without any knots or other thickened portions of the cord.
According to a further embodiment of the invention, the grip member comprises a recess in which the locking portion is arranged in such a manner that the recess and the locking portion form said passage. The locking portion may here by arranged to be displaceable in such a manner that the cord is fixedly clamped between the locking portion and a part of the recess as a consequence of a pulling load applied to the cord. Preferably, the cord, received by the grip member, extends in said passage in a loop, which at least partly encloses the locking portion. Thereby, it is obtained that the locking portion automatically is displaced by the pull-loaded cord and the locking portion will thus lock the cord in the passage. Advantageously, the locking portion comprises at least one edge for locking the cord. A further safer locking is obtained if the recess comprises one or more edges in the proximity of the edge of said locking portion.
According to a further advantageous embodiment of the invention, the recess of the grip member comprises a common inlet and outlet portion, respectively, of the passage for the cord. Thereby, the recess of the grip member is designed in an advantageous manner and the cord may in a simple way be applied to said recess.
According to another advantageous embodiment of the invention, the grip member comprises at least two releasably connected parts, which parts are kept together by said holding member and form said passage in a connected state. When mounting the cord-locking device, the cord is initially introduced into one of said parts, thereafter said parts are brought together, wherein the cord is received in the passage so formed. Thereafter, the cord is fastened in the holding member. The holding member is designed in such a manner that it keeps said connected parts together. When the cord is subjected to an unusually large pulling load, the grip member is released from the holding member, whereby the loosely connected parts of the grip member are released from each other and the cord may thereby be released from the grip member. Since said grip member may be used several times, it is advantageous if the grip member is manufactured as a unit and may be kept together by a flexible material section. Thereby, the disadvantage of looking for several loose parts which have fallen down to the ground when the grip member is to be used again is remedied. For reasons of costs, it is suitable to manufacture the grip member of a plastic material.
According to another advantageous embodiment of the invention, said holding member comprises at least two clamping elements arranged to clamp fixedly, between each other, the grip member in a connected state. Advantageously, the clamping elements are arranged to be resilient. By this design of the holding members, the parts of a gripping member may be kept together by the resilient force of the clamping elements. The connecting resilient force may be dimensioned in such a manner that the grip member is released from the holding member only when applying unusually large pulling loads to the cord.
According to a preferred embodiment of the invention, the cord-locking device is comprised by a safety coupling for automatic removal of a milking member. The cord is arranged, via a removing member, to be connected to a milking member of a milking machine. According to a further embodiment of the invention, the cord-locking device is comprised by a removing device for automatic removal of a milking member, wherein the removing device comprises an operating cylinder with a movable piston and a cord, wherein one end of the cord is connected to said milking member and its other end is connected releasably to said cord-locking device, and the cord between its end points is displaceably provided by the movable piston of the operating cylinder. In this type of removing device having an operating cylinder, it is particularly important that the cord does not have any knots or other members, since the cord during the releasing process is to be pulled through thin passages and holes in the operating cylinder. If the cord is fastened in, for instance, the operating cylinder, it may be damaged as well as the rest of the milking equipment and the cow.